Plunger plugs for hypodermic cartridges and methods of and apparatus for making the same



Jan. 17, 1956 E. E. TOMPKINS PLUNGER PLUGS FOR HYPODERMIC CARTRIDGES AND METHODS OF AND APPARATUS FOR MAKING THE SAME Filed March 8. 1951 INVENTOR. ERNEST E. TOMPKINS ATTORNEY.

United States Patent 2,730,766 PLUNGER PLUGS FOR HYPODERMIC CAR- TRIDGES AND METHODS OF AND AP- PARATUS FOR MAKING THE SAME Ernest E. Tompkins, Narberth, Pa., assignor to Tompkins Rubber Company, Plymouth Meeting, Pa., a corporation of Pennsylvania Application March 8, 1951, Serial No. 214,568

4 Claims. (Cl. 18-42) invention relates to apparatus for making plunger plugs for hypodermic cartridges.

,1 In the modern forms of hypodermic and intravenous injection devices, cartridges or ampuls containing the desired medication are commonly used. The cartridge or ampul is inserted into the barrel of the instrument, and

tridge may thus be caused to be discharged through the needle,.by pressing the plunger plug inwardly in the car- .Qtridge.

, The present invention relates only to apparatus for making plunger plugs of hypodermic cartridges or ampuls.

. Heretofore considerable ditficulty has been encountered in connection with the plunger plugs of the character aforesaid in that it was necessary, in preparing the carftridges or ampuls to receive the medication, to be sure that the finned edge, occurring from the flash or spill foyer of therubber in the emolding, was always disposed tbw ard the end of the cartridge as, otherwise, pieces of the fin might interfere with the subsequent free movement of the plungerplug and in some instances cause leakage or permit the spoiling of the contents in the cartridge through the entrance of air or other unsterilized substances. Of course, an effort was always made to mini- Tthe' amount of flash, not only for reasons of econdrnyin the rubber used, but also for the reasons above set forth, but in the administartion of medicaments, and l particularly those injected into the patients, it is not permissible totake any chances which may be avoided.

Thep'roblemds further complicated by the fact that fthe plunger plugs are usually provided with one or 'more circumferential grooves containing lubricants and sealing compounds.

The principal object of the present invention is to provide an apparatus for making plunger plugs for car tn'dges or ampuls to be used in hypodermic instruments, in which in each plug the residual portion of the fin, which results from the flash or spill over of the rubber in the mold, will be located at such position that the same will not interfere in any manner with the operation and proper functioning of the plug.

A further object of the invention is to provide apparatus for making a plunger plug of the character aforesaid, and which will eliminate the necessity of a careful selection of the proper end of the plug to insure that the finned edge will always be disposed toward the end of the cartridge.

The nature and characteristic features of the invention will be more readily understood from the following description, taken in connection with the accompanying drawing, forming part hereof, in which:

Figure 1 is a view partly in elevation and partly in section of a hypodermic cartridge or ampul having a 2,730,766 Patented Jan. 17, 1956 ice plunger plug made with the apparatus of the present invention mounted therein;

Fig. 2 is a side elevational view of one of the plugs detached;

Fig. 3 is a similar view illustrating one of the plugs before the major portion of the fin or flash has been removed therefrom;

Fig. 4- is a sectional view of a portion of a multiple mold for forming the plunger plugs illustrated in Figs. 1, 2 and 3; and

Fig. 5 is a plan view of one face of one part of the mold, the other part having been removed.

It should, of course, be understood that the description and drawing herein are illustrative merely, and that various modifications and changes may be made in the devices disclosed without departing from the spirit of the invention.

Referring now more particularly to Fig. 1 of the drawing, there is therein shown, partly in elevation and partly in section, a cartridge or ampul in connection with which a plunger plug made with the apparatus of the present invention is used, said cartridge comprising a cylindrical glass tube 10 having a plug 11 at the discharge end thereof, the formation of and characteristics of which are at present of no particular concern.

At one end of the tube 10 there is internally mounted one of the plunger plugs 12 made with the apparatus of the present invention, the same comprising a cylinder of soft rubber, both of the end edges of which are slightly rounded as at 13, and having a centrally disposed annular groove 14.

The mold of the present invention is shown more particularly in Figs. 4 and 5 of the drawing. As there shown the same is made in two parts 15 and 16, each with a plurality of registered mold cavities 17. Each of the mold cavities is provided, adjacent the parting face of the part of the mold in which the cavity is located, with an inwardly extending annular flange 19 which, in conjunction with the similar flange of the complemental mold cavity 17 in the other part of the mold, forms the annular groove 14 of the plunger plug.

The parting line of the mold where the flash or overflow occurs is therefore midway the width of the annular groove 14 of the plunger plug so that any residue of the fin 20 left where the flash or overflow occurs will be entirely within the groove 14.

The process of making the plugs is comparatively simple, as it is only necessary to place in each mold cavity of one part of the mold a suflicient quantity of raw or unvulcanized rubber of the amount required to form the plug, and then when the two parts of the mold are forced together the excess rubber will be squeezed out between the faces of the mold into the overflow spaces 21 surrounding the mold cavities.

The plugs, after being thus formed, are vulcanized in the mold after which the mold is separated, and it will be found that approximately half of the plugs will remain in one part of the mold, and the other half will be in the other part of the mold. However, the plugs may then be readily removed from the several parts of the mold .by the mere pushing action of the operators hand. The plugs may then be tumbled, while in a very low temperature condition to remove the major portions of the fins resulting from the overflow.

It will be found that a plug made as aforesaid will be characterized by the absence of fins at both ends of the plug. Hence, there will be no necessity for any selectivity, as the same are mounted in the end of the cartridge, and in each instance any residue of the fin which may remain will be in the bottom of the annular groove where no harm can result therefrom.

her.

in the cartridge tubes.

or overflow of the rubber during the molding of the plugs.

The foregoing arrangement and structure of the mold permits the end marginal edges of the plug to be slightly rounded and positively prevents the formation of a fin at either end of the plug.

The plunger plugs made with the apparatus of the present invention have been found to function much more satisfactorily than the plugs heretofore made. The use of the same results in the elimination of the necessity to carefully'examine each end of each plug to insure that the same is not inserted in the cartridge tube fin end foremost, and also results in the elimination of leakage, either inwardly or outwardly with respect to the plunger plug by reason of portions of the fin being disposed between the outer face of the plug and the inner face of the wall of the cartridge tube mem- Furtherrnore, the plugs made in accordance with thepresent invention will at all times slide more freely The present invention is of particular importance by reason of the absolute necessity for the prevention of-faulty technique in the administration of the medication in connection with which the plunger plugs are used.

' I claim:

1, Arnold for forming plunger plugs of rubber or the like, for use in hypodermic cartridges or ampuls, comprising two mold members each having registering mold cavities, each of said mold members having an inwardly extending flange at each cavity, said flanges being located immediately adjacent the parting faces of the mold members, the arrangement being such that an annular groove will be formed in each plug intermediate the ends thereof, and any residual fins resulting from the overflow from the mold cavities will occur in each plug at the base of said annular groove.

2.'A mold for forming plunger plugs of rubber or the like, for use in hypodermic cartridges or ampuls,

comprising two moldmembers each having registering mold cavities, the mold cavities of one of said members being substantially similar in size and shape to the mold cavities of the other member, each of said mold mem- Cir intermediate the ends thereof, and any residual fins resulting from the overflowfrom the mold cavities will occur in each plug at the base of said annular groove, the mold being interiorly shaped to form the plug with straight cylindrical working surfaces.

3. A mold for forming plunger plugs of rubber or the like, for use in hypodermic cartridges or ampuls, comprising two mold members each having registering mold cavities, the mold cavities of one of said members being substantially similar in size and shape to the mold cavities of the other member, each of said mold members having an inwardly extending flange at each cavity with a rounded inner face, said-flanges being located immediately adjacent the parting faces of the mold members, the arrangement being such that an annular groove will be formed in each plug intermediate the ends thereof, and any residual fins resulting from V the overflow from the mold cavities will occur in each plug at the base of said annular groove, the mold being interiorly shaped to form the plug with straight cylindrical working surfaces.

4. A mold for forming plunger plugs of rubber or the like, for use in hypodermic cartridges or ampuls, comprising two mold members each having registering mold cavities, the mold cavities of one of said members being substantially similar in size and shape to the mold cavities of the other member, each of said mold members having an inwardly extending flange at each cavity with a rounded inner face, said flanges being located immediately adjacent the parting faces of the mold members, the arrangement being such that an annular groove will be formed in each plug intermediate the ends thereof, and any residual fins resulting from the overflow from the mold cavities will occur in each plug at the base of said annular groove, the mold being interiorly shaped to form the plug with straight cylindrical working surfaces, and the marginal portionat the base of each of the mold cavities being shaped to provide slightly rounded edges at both ends of the plug which is formed therein.

References Cited in the file of thispatent UNITED STATES PATENTS 447,555 Beyer Mar. 3, 1891 587,961 Hardman "Aug. 10, 1897 1,624,224 Easterlin Apr. 12, 1927 1,687,797 Sachse Oct. 16, .1928 1,817,287 Bell Aug 4, 1931 1,951,924 Clark Mar. 20, 1934 2,063,355 Wheway Dec. 8', 1936 2,353,674 Kimber July 18, 1944 

